Learning parameters displayed in
the statistics window:
- Date - current date and the day of the week. If this
value is preceded with Night, it means that the new day has already started but
the old repetition day will still last as long as defined in Midnight clock shift. In the
example on the right, the picture snapshot was taken past midnight on
the first day of spring 2002 (Thursday). The collection in use is named
"all" as shown in the caption
- First day - date on which the learning process began
(i.e. the day on which the first element was memorized). The
exemplary collection presented in the picture has been in use since December 15, 1987 (i.e.
the birth date of SuperMemo for
DOS)
- Day - number of days in the learning process (i.e.
number of days between Date and First day).
Day=Date-First day.
The presented collection has been in use for 5211 days (i.e. 14 years
and 97 days)
- Total - the number of items, topics and tasks in
the collection.
Memorized+Pending+Dismissed=Total.
Deleted elements do not contribute to the total count of elements in the system. In
the picture, the presented collection is made of near 137,000 elements
- Items+Topics - the number of items and the number of topics
(and tasks) in the collection.
Items+Topics=Total.
In the example, the collection includes over 82,000 items and over
54,000 topics (or tasks)
- Memorized
- total number of elements introduced into the learning process with options such
as Learn
or Remember. If an item takes part in repetitions it is a memorized
item. It does not mean it is a remembered item (see FAQ). The
presented collection has nearly 116,000 elements in the learning process and these
elements make up 94.7% of all elements in the collection, i.e.
Memorized/Total=0.947
- Memorized items - the number of memorized items in the
collection and the proportion of memorized items among memorized
elements. In the example, about 73,500 items take part in
repetitions. These items make 63.5% of all memorized elements. The
retention field (below) indicates that 94.11% of these items should be
remembered at any given time
- Memorized topics - the number of memorized topics and the
proportion of memorized topics among all memorized elements. In the
example, over 42,000 topics make 36.5% of the material taking part in
the learning process. In incremental reading, topics easily make a half
of the material taking part in repetitions
- Memorized/Day - number of elements memorized in the
collection per day. In the example, the average of 22.2 elements
have been memorized daily in
the presented collection over the last 14 years
- Pending
- the number of
elements (topics or items) that have not yet been introduced into the
learning process but still await memorization with Learn, Remember,
etc. All pending elements are kept in the so-called pending
queue that determines the sequence of learning new elements. Dismissed items are not
kept in the pending queue. In the example, the collection contains
6491 elements in the pending queue. With incremental
reading and selective postpone tools, the role of the pending queue
in SuperMemo is diminishing
- Dismissed - the number of elements (topics, items
or tasks) that have been excluded from the learning process and are kept only as reference
material, knowledge tree skeletal material, or tasklist material. Dismissed items are neither pending nor memorized.
All tasks are dismissed by default, i.e. they usually do not take part in repetitions. In
the example, nearly 15,000 elements have been dismissed. In incremental
reading, you will often keep parent articles for context and
reference until children items are full formulated, moved to their
target categories and provided with all necessary context. This is why
the proportion of dismissed material is often quite high in collections
subject to incremental reading
- Outstanding
- number of
outstanding items, outstanding topics and final drill items scheduled for repetition on
this given day. The first number (before the
plus sign) indicates the number of items scheduled for this given day and not yet
processed. The second number (after the plus sign) indicates number of
topics scheduled for review for this day. The third number (after the
second plus sign), if present, indicates the number of items that have
already been repeated today but scored less than Good (4). Those are the items that
make up the final drill queue. The final drill queue is built only if Skip
final drill is unchecked in Options. In the presented collection,
there are still 64 items scheduled for repetition on March 21, 2002.
There are also 350 topics scheduled for review on that day (most likely
as part of incremental reading). There are no elements in the final
drill queue (the third components of Outstanding is missing)
- Retention - estimated knowledge retention in the collection. In the example, nearly 95% of the material should be recalled in a
random test on all elements in the collection at any time. You can test your retention using random
tests and see if SuperMemo's estimates are accurate. This
statistic may be overly optimistic if you abuse rescheduling tools such
as Postpone or Mercy
- Measured FI -
the value of the measured forgetting index as
recorded during repetitions. The measured forgetting index is the proportion of items not
remembered during repetitions. The number in the parentheses indicates Measured FI
for the current session (i.e. since the opening of the collection). It is quite usual to have Measured FI higher than Average
FI. This is due to two factors: (1) every user
will experience delays in repetitions from time to time (e.g. as a
result of using Postpone), (2) SuperMemo imposes some
constraints on the length of intervals that, in some cases, make it schedule repetitions
later
than it would be implied by the forgetting index. The constraints in computing intervals,
for example, prevent the new interval from being shorter than the old interval
(assuming the items has not been forgotten). For low values of the forgetting index and
items with a low A-Factor, the new optimum interval might often be
shorter than the old one! In the presented example, 11.54% of repetitions end with
grades less than Pass (since the measured forgetting index record was
last reset). In the current session on Mar 21, 2002, 11.5% of item
repetitions ended in failure (i.e. grade less than Pass (3))
- Average FI - the average requested
forgetting index in the entire collection (the number in
parentheses is the default forgetting index). If the forgetting index of individual elements
is not changed manually, Average FI is equal to the default forgetting index as set
in Tools : Options : Learning : Forgetting index. The
default forgetting index is the requested forgetting index given to all
categories and, as a result, to all new items added
to the collection. Forgetting index, in general, is the proportion of items that are not
remembered during repetitions. The lower the value of the forgetting index the better the
recall of the element, but the more repetitions will be needed to keep it in memory.
Optimum value of the forgetting index falls into the range from 7% to 13%. Too low
a forgetting index makes learning too tiresome due to a prohibitively large number of
repetitions. All elements can have their desired forgetting index set individually. The
easiest way to change the forgetting index of a large number of elements is to use Forgetting
index option on the contents menu in the contents window
or in the browser.
In the presented example, the average forgetting index is 10.07% while the default
forgetting index is 10%. See: Using forgetting index
- Burden -
estimation of the average number of
repetitions per day. This value is equal to the sum of all
interval reciprocals (i.e.
1/interval). The interpretation of this number is as follows: every item with interval of
100 days is on average repeated 1/100 times per day. Thus the sum of
interval reciprocals is
a good indicator of the total repetition workload in the collection. The presented
collection requires about 752 repetitions per day. In incremental
reading, it is not unusual to have many more topics in the process than
one can handle. Postpone can be used to unload the excess of
topics at the end of the learning day or session
- Burden +/- - the change of the Burden parameter
above in the present session. Here, on Mar 21, 2002, the average number of
expected repetitions
increased by 17.3 elements per day. This large increase could come from
a heavy use of incremental reading tools that make it possible to
schedule new extracts with the new interval of one day. 17 such extracts
would increase Burden by 17*(1/1)=17 items per day
- Workload - the average daily time used for responding
to questions in a given collection.
Workload = Burden*Avg. time. In the presented collection,
752 repetitions per day taking 8.5 seconds each result in a daily repetition time
estimation of over 1 hours and 46 minutes. A real learning session
may be twice longer due to grading, editing, reviewing the collection and
various interruptions. It may also be much shorter if Postpone is
used
- Subset - number of
elements scheduled for subset repetition (e.g. elements in the
random test queue in Tools :
Random tests, elements in
branch repetitions in Contents : Learn,
elements in a browser subset repetitions in browser's Learn,etc.).
The display may have a form of <items left>+<topics lef>+<pending
left>+(<subset type>) in subset tests, or <elements
unprocessed>/<all elements in the test> in random tests.
Here 64 elements are scheduled for subset review. None of these are
pending (i.e. all are memorized). In incremental
reading, subset repetitions are most often executed in the contents
window or in the browser with Learning : Learn (Ctrl+Alt+L) or
with Learning : Review. In the later case, not only outstanding
elements are reviewed. The remaining elements are subject to
mid-interval review as well
- Rep count - the total count of repetitions made in
the collection. In the presented collection, 771 thousand repetitions have been made.
This is about 6.7 repetitions per memorized element (this count includes repetitions of items
that have been reset, forgotten, dismissed, deleted, etc.)
- Time - total question response time in the current session and
the total session time (in parentheses). Here the total time needed to respond to
questions in the current sessions was 4 minutes and 30 seconds in a session that has
lasted over 1 hour and 46 minutes. Significant differences in response
and session time occur when the
collection is intensely edited, in incremental reading (passive review
does not contribute to response time) or when the user simply takes a
break from learning
- Avg. time - average response time in seconds (i.e.
the time between displaying the question and choosing Show answer or
equivalent). In the presented collection, the average time to answer a single question
is over 8.5 seconds. If this number grows beyond 10-20 seconds, you may
need to analyze your learning material if it is not overly difficult or
badly structured
- Total time - total time taken by responding to
questions in the collection. This time cannot be accurately measured for collections
created with SuperMemo 98 or earlier. The exact measurements of
this parameter were only made possible in SuperMemo 99. If you upgrade your collections to
SuperMemo 99, SuperMemo will assist you in estimating this number. If
you upgrade directly to a later version, this number will roughly be
guessed for you. SuperMemo will derive this time from the total number of items, average number of
repetitions, average number of lapses and the average repetition time. In the
presented example, answering questions during repetitions took over 113 days
of non-stop learning (in 14 years of the learning process)
- Lapses - average number of times individual
items have been forgotten in the collection (only memorized elements are averaged). The number
in parentheses shows the number of lapses in the current session. Here an average
element has been forgotten 0.587 times. In the presented session, three lapses
have
occurred
- Speed - the average
knowledge acquisition rate, i.e. the number of items memorized per year per minute of
daily work. Initially this value may be as high as 100,000 items/year/minute (esp. if you
enthusiastically start working with the program before truly measuring its limitations;
or rather the limitations of your memory); however, it should with time stabilize between
40 and 400 items/year/minute. In the presented collection, every minute of work per
day resulted in 48 new items memorized each year. As this value is
derived from Burden, it may be highly underestimated if you use Postpone
a lot (e.g. in incremental reading)
- Cost - the cost in time of memorizing a single item,
i.e. total learning time divided by the number of memorized items. Cost = Total
time / Memorized
In the presented example, the total repetition time per single item is
1.4 minutes. In
other words, each item has contributed 1.4 minutes to the total of non-stop
113 days and 19 hours of repetitions. The cost of editing,
restructuring, incremental reading, etc. is not included in this number
- Daily cost - daily repetition time per each newly
memorized item.
Daily cost = Workload / (Memorized/Day)
In the presented collection, each of the 22 newly memorized items per day contributes
about 4.8 minutes of repetitions to the total workload of 1 hour 46 minutes per day.
As this value is derived from Burden, it may be highly
underestimated if you use Postpone a lot (e.g. in incremental
reading)
- Interval - average interval
among memorized elements in the
collection. Here an average memorized element has reached the average interval
of 860 days
- Repetitions - average number of repetitions per
memorized element in the collection. Here an average element has been repeated
4.4 times
- Last Rep - average date of the last repetition among
memorized elements in the collection. Here the average date of the last repetition
is October 10, 2000
- Next Rep - average date of the next repetition among
memorized elements in the collection.
Next Rep = Last Rep + Interval
Here the average date of the next repetition is February 18, 2003 or
860 days after October 10, 2000
- Completion - the expected date on which all elements
from the pending queue will be memorized assuming the present rate of learning new items.
Completion=Date+(Pending/(Memorized/Day))
In the example, it would take until January 2003 to memorize all 6491 pending items
at the speed of 22 items per day (beginning with March 21, 2002)
- A-Factor - average value of A-Factor
among memorized items in the collection. A-Factor is a measure of item difficulty. The
higher the A-Factor, the easier the item. In the presented collection, the average
A-Factor is about 4.09. This indicates that the collection is rather well-structured and
the material is thus relatively easy to remember
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